You built an internal app with Claude Code or Cursor. It works. The logic is solid. Your team wants to use it tomorrow. Then your CTO asks: "How do our people log in with their Okta credentials?" And suddenly you are spending the next 2 weeks not shipping the tool your team needs, but wrestling with OAuth flows, token validation, session management, and edge cases you did not know existed. This guide will get you from zero to production SSO. You will understand how OIDC actually works, see a full implementation you can copy, learn where the real complexity hides, and choose the approach that fits your situation. Or, if you just want SSO working in 10 minutes, skip straight to the easy path .…